Damage-indicating medical cannula

ABSTRACT

An example medical device includes a body portion having a tubular inner wall defining an inner channel, and a tubular outer wall encircling the inner wall. The outer wall defines an outer channel between the outer wall and the inner wall. The body portion also includes an indicator substance disposed within the outer channel. The device also includes an indicator portion defining an indicator channel. The body portion is configured to insert at least in part into a patient, and the indicator portion is configured to remain at least in part along an exterior of the patient when the body portion is inserted into the patient. The device is also configured to transfer at least a portion of the indicator substance from the outer channel to the indicator channel when the body portion is bent.

TECHNICAL FIELD

This disclosure relates to medical cannulas.

BACKGROUND

A medical cannula is a tube-like device that can be inserted into thebody of a patient, often for the delivery of fluid into the patient orthe removal of fluid from the patient. As an example, a user can attachone end of a medical cannula to a vessel containing a therapeuticsubstance (e.g., a container of an insulin solution), and insert theopposite end of the medical cannula into a patient's body (e.g., bypressing a tip of the cannula against the patient's body until itpierces the patient's skin). This creates a fluid pathway between thevessel and the interior of the patient's body, and facilitatesadministration of the therapeutic substance.

During use, a medical cannula may be bent or “kinked.” For example, whenthe tip of the medical cannula is pressed against the patient's body,the tip may be deflected by the patient's body (e.g., the patient's skinor structures under the patient's skin). As a result, the medicalcannula may be bent, resulting in the crimping and obstruction of thecannula's inner channel. This can interfere with the flow of fluid intoor out of the patient, and can negatively impact the patient'streatment.

In some cases, it is difficult for a user to visually ascertain whethera medical cannula is bent or kinked. For example, the tip of the medicalcannula may be obscured when it is pressed against the user's body(e.g., by other structures of the medical cannula, objects attached themedical cannula, the patient's body, and so forth). Thus, in some cases,a user may have difficulty determining whether therapeutic substancesare being properly administered to a patient.

SUMMARY

Implementations of a damage-indicating medical cannula are describedherein. Implementations of the medical cannula enable a user to visuallyascertain whether a cannula has been bent or kinked during insertion oruse. This is beneficial, for example, as it enables the user and/orpatient to efficiently identity and replace a faulty medical cannula,such that the patient's quality of care is not negatively impacted.

In general, in an aspect, a medical device includes medical device abody portion having a tubular inner wall defining an inner channel, anda tubular outer wall encircling the inner wall. The outer wall definesan outer channel between the outer wall and the inner wall. The devicealso includes an indicator substance disposed within the outer channel.The device also includes an indicator portion defining an indicatorchannel. The body portion is configured to insert at least in part intoa patient, and the indicator portion is configured to remain at least inpart along an exterior of the patient when the body portion is insertedinto the patient. The device is also configured to transfer at least aportion of the indicator substance from the outer channel to theindicator channel when the body portion is bent.

Implementations of this aspect can include one or more of the followingfeatures.

In some implementations, the outer channel and the indicator channel canbe separated by a frangible membrane, and the frangible membrane can beconfigured to rupture when the body portion is bent.

In some implementations, the indicator channel and the outer channel canbe in fluid communication upon rupture of the frangible membrane.

In some implementations, the indicator portion can include a transparentor translucent surface, and an interior of the indicator channel can bevisible through the transparent or translucent surface when the bodyportion is inserted into the patient.

In some implementations, the indicator substance can include a coloreddye.

In some implementations, the indicator channel can contain a reactivesubstance. Transferring at least the portion of the indicator substancefrom the outer channel to the indicator channel can cause a reactionbetween the indicator substance and the reactive substance.

In some implementations, the reaction can cause the indicator substanceto change color.

In some implementations, the indicator portion can be disposed along afirst end of the outer channel.

In some implementations, the indicator portion can be disc shaped.

In some implementations, the device can further include an adapterportion. The adapter portion can define an access channel through theinner wall and the outer wall. The access channel can be in fluidcommunication with the inner channel.

In some implementations, the adapter portion can be configured tophysically couple to a vessel containing a fluid. The device can beconfigured to deliver the fluid from the vessel to the patient throughthe access channel and the inner channel.

In some implementations, the fluid can include insulin.

In some implementations, the device can further include a reservoircontaining a fluid. The reservoir can be in fluid communication with theinner channel.

In some implementations, the fluid can include insulin.

In some implementations, the device can further include an interfacematerial positioned within the indicator channel.

In some implementations, the interface material can be a sponge.

In general, in another aspect, a medical device includes a body portionhaving a tubular inner wall defining an inner channel, and a tubularouter wall encircling the inner wall. The outer wall defines an outerchannel between the outer wall and the inner wall. The device alsoincludes an indicator substance disposed within the outer channel. Thebody portion is configured to insert at least in part into a patient,and the device is configured to release at least a portion of theindicator substance from the outer channel to an exterior of the medicaldevice when the body portion is bent.

Implementations of this aspect can include one or more of the followingfeatures.

In some implementations, the indicator substance can be an irritant.

In some implementations, the outer wall can be configured to rupturewhen the body portion is bent.

In general, in another aspect, a medical device includes a body portionhaving a tubular wall defining an inner channel, a first layer affixedto the wall, and a second layer affixed to the first layer. The devicealso includes an electronic control module in electrical communicationwith the first layer. The body portion is configured to insert at leastin part into a patient, and the second layer is configured to rupturewhen the body portion is bent to expose the first layer to an exteriorof the medical device. The first layer is configured to generate anelectrical response upon contacting a interstitial fluid in anenvironment surrounding the medical device, and the electronic controlmodule is configured to detect the electrical response and generate anindication to a user based on the detected electrical response.

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other features and advantages willbe apparent from the description and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram of an example medical cannula.

FIGS. 2A and 2B are diagrams depicting the use of an example medicalcannula.

FIGS. 3A-3C are diagrams depicting the use of an example medical cannulathat has been damaged during use.

FIGS. 4A-4C are diagrams depicting the use of another example medicalcannula that has been damaged during use.

FIGS. 5A-5C are diagrams depicting the use of another example medicalcannula that has been damaged during use.

FIGS. 6A and 6B are diagrams depicting the use of another examplemedical cannula that has been damaged during use.

FIGS. 7A and 7B are diagrams depicting the use of another examplemedical cannula that has been damaged during use.

FIGS. 8A and 8B are diagrams of example body portions of an medicalcannula.

FIG. 9 is a diagram of another example medical cannula.

DETAILED DESCRIPTION

Implementations of a damage-indicating medical cannula are describedherein. Implementations of the medical cannula enable a user to visuallyascertain whether a cannula has been bent or kinked during insertion oruse. In some cases, implementations of the medical cannula can be usedto deliver a therapeutic substance (e.g., an insulin solution) to aninterior of a patient, and enable a user to visually determine whetherthe therapeutic substance is being properly delivered. In some cases,implementations of the medical cannula can also provide tactile feedbackto the patient and/or transmit electronic messages when it has been bentor kinked. This is beneficial, for example, as it enables the userand/or patient to efficiently identity and replace a faulty medicalcannula, such that the patient's quality of care is not negativelyimpacted.

An example implementation of a damage-indicating medical cannula 100 isshown in FIG. 1. The medical cannula 100 includes a body portion 110, anindicator portion 120, and an adapter portion 130. In this example, thebody portion 110 extends along an axis of extension 140, and theindicator portion 120 is disposed atop the body portion 110 along theaxis of extension 140. The adapter portion 130 protrudes from the bodyportion 110 (e.g., in a direction approximately orthogonal to the axisof extension 140).

FIG. 2A shows a cross-section of the medical cannula 100 along a planeparallel of the axis of extension 140.

The body portion 110 is generally tubular in shape. The body portion 110includes a tubular inner wall 202 that defines an inner channel 204. Thebody portion also includes a tubular outer wall 206 that encircles theinner wall 202, such that an annular outer channel 208 is definedbetween the inner wall 202 and the outer wall 206. The inner channel 204and the outer channel 208 are in fluid isolation with respect to oneanother, such that the contents of the inner channel 204 and the outerchannel 208 do not mix.

The outer channel 208 contains an indicator substance 210. In theexample shown in FIG. 2A, the indicator substance 210 is a colored dye(e.g., a solution having a visually discernable color, such as red,green, blue, black, or any other color). However, the indicatorsubstance 210 need not be colored. As the inner channel 204 and theouter channel 208 are in fluid isolation with respect to one another,the indicator substance 210 is securely contained within the outerchannel 208, and cannot escape into the inner channel 204.

The indicator portion 120 is generally disc-like in shape, and ispositioned above the body portion 110. The indicator portion 120 definesan indicator channel 212. The indicator channel 212 and the outerchannel 208 are separated by an annular frangible membrane 214. When thefrangible membrane 214 is intact, the indicator channel 212 and theouter channel 208 are in fluid isolation with respect to one another,such that the contents of the indicator channel 212 and the outerchannel 208 do not mix. In some cases, the indicator channel 212contains air or is a vacuum. In some cases, the indicator channel 212contains a fluid having a different color than that of the indicatorsubstance 210 (e.g., a clear fluid, a white fluid, or some othercontrasting color). In some cases, the indicator channel 212 contains afluid-sensitive material, such as a paper, sponge, or other materialthat changes color when contacted by a fluid (e.g., the indicatorsubstance 210).

The adapter portion 130 protrudes from the body portion 110, and definesan adapter channel 216 that is in fluid communication with the innerchannel 204. Fluids introduced into a receiving end 218 of the adapterportion 130 are guided to the exit end 220 of the body portion 110.

The medical cannula 100 can be used to deliver a fluid (e.g., atherapeutic substance, such as an insulin solution) into a patient. Toillustrate, FIG. 2B shows the medical cannula 100 inserted into apatient's body 222. The medical cannula 100 can be inserted, forexample, by pressing the medical cannula 100 against the patient's body222, such that the exit end 220 of the body portion 110 pierces thepatient's skin 224. In some cases, the edges of the exit end 220 can besharpened or beveled to facilitate insertion into the patient's body222.

The receiving end 218 is attached to a vessel 226 containing a fluid(e.g., a container of a therapeutic substance, such as an insulinsolution). Accordingly, fluid from the vessel 226 is introduced into thereceiving end 218 of the adapter portion 130 and guided by the adapterchannel 216 and the inner channel 204 to the exit end 220 of the bodyportion 110. As the exit end 220 of the body portion 110 is beneath thepatient's skin 224, the fluid is released beneath the patient's skin224. In some cases, fluid from the vessel 226 can be propelled from thevessel 226 and/or through the medical cannula 100 by a pump (e.g., asyringe pump or an electronic pump), or by some other device thatapplies pressure or suction.

In the example shown in FIG. 2B, the medical cannula 100 has not beendamaged during operation. For instance, the body portion 110 has beeninserted into the patient's body 222 in such a way that the inner wall202 and the outer wall 206 remain straight and unbent. Thus, the innerchannel 204 is not obstructed, and fluid can freely flow from the vessel226 into the patient's body.

However, during use, the medical cannula 100 may become damaged. Forexample, in some cases, the medical cannula may bend or kink during use,which may obstruct the inner channel 204 and restrict the free flow offluid into the patient.

To illustrate, FIG. 3A shows the medical cannula 100 inserted into apatient's body 222. As with the example shown in FIG. 2B, the medicalcannula 100 can be inserted by pressing the medical cannula 100 againstthe patient's body 222, such that the exit end 220 of the body portion110 pierces the patient's skin 224. However, in this example, the innerwall 202 and the outer wall 206 have been bent during insertion (e.g.,due to the exit end 220 being deflected by the patient's skin 224 and/orstructures below). Thus, the inner channel 204 is also bent. The bendingof the inner wall 202 and the outer wall 206 increases the fluidpressure within the outer channel 208 (e.g., due to a decrease in thesize of the outer channel 208 as a result of the bending).

As shown in FIG. 3B, as the medical cannula 100 is further pressedagainst the patient's body 224, the inner wall 202 and the outer wall206 increasingly bend. As a result, the inner channel 204 is crimped andbecomes obstructed, thereby impeding the flow of fluid from the vessel226 into the patient. In addition, the fluid pressure within the outerchannel 208 is further increased (e.g., due to further decrease in thesize of the outer channel 208 as a result of the bending). If the fluidpressure becomes sufficiently high, the frangible membrane 214 ruptures,releasing the indicator substance 210 into the indicator channel 212.

As shown in FIG. 3C, the release of the indicator substance 210 into theindicator channel 212 can be visually observed by a user. For example,the indicator portion 120 can include one or more transparent ortranslucent surfaces 228 that enable the user to view the interior ofthe indicator channel 212. Upon the rupture of the frangible membrane214, the user observes a change in color within the indicator channel212 (due to the introduction of the indicator substance 210 into theindicator channel 212). Based on this observation, the user ascertainsthat the body portion 110 has been bent or kinked, and that the medicalcannula 100 is damaged. Accordingly, the user can replace the damagedmedical cannula 100 (e.g., by removing the medical cannula 100 andreinserting a new or repaired medical cannula 100).

The release of the indicator substance 210 into the indicator channel212 can be made more conspicuous in various ways. For example, theindicator channel can be initially empty (e.g., filled with air or in astate of vacuum), and the interior surface of the indicator channel 212can have a color that it different than that of the indicator substance210. Thus, when the indicator substance 210 is released in the indicatorchannel 212, the indicator substance 210 is readily observable by achange in color. To illustrate, the interior of the indicator channel212 can be white, and the indicator substance 210 can be blue. Thus, theinterior of the indicator channel 212 appears white when the medicalcannula 100 is undamaged, and appears blue when the medical cannula 100is bent or kinked.

As another example, the interior of the indicator channel 212 cancontain a liquid having a color that it different than that of theindicator substance 210. Thus, when the indicator substance 210 isreleased in the indicator channel 212, the indicator substance isreadily observable by a change in color. To illustrate, the indicatorchannel 212 contain a liquid having a clear color, and the indicatorsubstance 210 can be black. Thus, the liquid in the indicator channel212 appears clear when the medical cannula 100 is undamaged, and appearsblack when the medical cannula 100 is bent or kinked.

As another example, the interior of the indicator channel 212 cancontain a fluid-sensitive material, such as a paper, sponge, or othermaterial that changes color when contacted by a fluid. Thus, when theindicator substance 210 is released in the indicator channel 212, theindicator substance is readily observable by a change in color. Toillustrate, the indicator channel 212 contain a fluid-sensitive materialhaving a white color when dry, and a red color when wet (e.g., when itcomes into contact with the indicator substance 210). Thus, the materialin the indicator channel 212 appears white when the medical cannula 100is undamaged, and appears red when the medical cannula 100 is bent orkinked.

Although example combinations of colors are described above, these aremerely illustrative examples. In practice, any combination of colors canbe used to visually indicate the condition of the medical cannula 100.

Although FIGS. 3A-3C show an example usage in which a medical cannula100 is bent or kinked beneath the surface of a patient's skin, this neednot be the case. For example, in some cases, a medical cannula 100 canbend or kink at a point above the surface of the patient's skin, suchthat the tip of the medical cannula 100 does not pierce the patient'sskin at all. As another example, in some cases, a medical cannula 100can bend at multiple points, including one or more points above thesurface of the patient' s skin and one or more points beneath thesurface of the patient's skin.

Further, although FIG. 3B shows the frangible membrane 214 rupturingwhen the inner wall 202 and outer wall 206 experience a particulardegree of bending, this is merely an illustrative example. In practice,the frangible membrane 214 can be configured such that it ruptures whenthe inner wall 202 and outer wall 206 experience any specified degree ofbending. For example, the frangible membrane 214 can be designed suchthat it ruptures if the inner wall 202 and/or the outer wall 206experience any bending at all. As another example, the frangiblemembrane 214 can be designed such that it ruptures only if the innerwall 202 and/or the outer wall 206 experiences a degree of bendingsufficient to obstruct the inner channel 204. In some cases, this can beachieved by configuring the frangible membrane 214 such that it rupturesin response to a pre-defined fluid pressure within the outer channel208.

In some cases, a medical cannula 100 can provide a visual indication ofdamage through a chemical reaction between two solutions. To illustrate,FIG. 4A shows the medical cannula 100 inserted into a patient's body222. In this example, the indicator channel 212 contains a chemicallyreactive substance 302 that produces in a visually discernable chemicalreaction when combined with the indicator substance 210 contained withinthe outer channel 208. The chemically reactive substance 302 and theindicator substance 210 are separated by the frangible membrane 214.

As with the example shown in FIG. 3A, the medical cannula 100 can beinserted by pressing the medical cannula 100 against the patient's body222, such that the exit end 220 of the body portion 110 pierces thepatient's skin 224. Similarly, in this example, the inner wall 202 andthe outer wall 206 have been bent during insertion (e.g., due to theexit end 220 being deflected by the patient's skin 224 and/or structuresbelow). Thus, the inner channel 204 is also bent. The bending of theinner wall 202 and the outer wall 206 increases the fluid pressurewithin the outer channel 208 (e.g., due to a decrease in the size of theouter channel 208 as a result of the bending).

As shown in FIG. 4B, as the medical cannula 100 is further pressedagainst the patient's body 224, the inner wall 202 and the outer wall206 increasingly bend. As a result, the inner channel 204 is crimped andbecomes obstructed, thereby impeding the flow of fluid from the vessel226 into the patient. In addition, the fluid pressure within the outerchannel 208 is further increased (e.g., due to further decrease in thesize of the outer channel 208 as a result of the bending). If the fluidpressure becomes sufficiently high, the frangible membrane 214 ruptures,releasing the indicator substance 210 into the indicator channel 212.

As shown in FIG. 4C, the release of the indicator substance 210 into theindicator channel 212 causes a chemical reaction with the chemicallyreactive substance 302 (depicted by the change of shading of theindicator channel 212). The chemical reaction between the indicatorsubstance 210 and the chemically reactive substance 302 can be visuallyobserved by a user. For example, the chemical reaction can result in achange of color (e.g., from a clear color to a red color), a change inclarity (e.g., through the creation of a precipitate), a change inphotoluminescence, or a change in any other visually discernableproperty of the combined substances.

Further, in a similar manner as shown in FIG. 3C, the indicator portion120 can include one or more transparent or translucent surfaces 228 thatenable the user to view the interior of the indicator channel 212. Uponthe rupture of the frangible membrane 214, the user observes thechemical reaction within the indicator channel 212 (due to thecombination of the indicator substance 210 and the chemically reactionsubstance 302). Based on this observation, the user ascertains that thebody portion 110 has been bent or kinked, and that the medical cannula100 is damaged. Accordingly, the user can replace the damaged medicalcannula 100 (e.g., by removing the medical cannula 100 and reinserting anew or repaired medical cannula 100).

In some cases, a medical cannula 100 can also include an interfacematerial within the indicator channel 212 that further separates thecontents of the outer channel 208 from the indicator channel 212. Toillustrate, FIG. 5A shows the medical cannula 100 inserted into apatient's body 222. As with the example shown in FIG. 4A, the indicatorchannel 212 contains chemically reactive substance 302 that produces ina visually discernable chemical reaction when combined with theindicator substance 210 contained within the outer channel 208. Thechemically reactive substance 302 and the indicator substance 210 areseparated by the frangible membrane 214 and by an interface material502. The interface material 502 is porous or semi-porous, such thatfluids can permeate or diffuse through it. As an example, the interfacematerial 502 can be a sponge, a paper, a fibrous material, a matrixmaterial, or some other porous or semi-porous material.

In some cases, the interface material 502 can be directionallydependent, such that fluids can only permeate or diffuse through it insubstantially one direction (e.g., in a direction from the outer channel208 towards the indicator channel 212, but not in the oppositedirection). In some cases, the interface material 502 can have diffusiveproperties that are dependent on fluid type or particle size, such thatonly particular types of fluids and/or particular sized particles cansubstantially permeate or diffuse through it (e.g., allowing for thediffusion of the indicator substance 210 across it, but not thediffusion of the chemically reactive substance 302).

As with the example shown in FIG. 4A, the medical cannula 100 can beinserted by pressing the medical cannula 110 against the patient's body222, such that the exit end 220 of the body portion 110 pierces thepatient's skin 224. Similarly, in this example, the inner wall 202 andthe outer wall 206 have been bent during insertion (e.g., due to theexit end 220 being deflected by the patient's skin 224 and/or structuresbelow). Thus, the inner channel 204 is also bent. The bending of theinner wall 202 and the outer wall 206 increases the fluid pressurewithin the outer channel 208 (e.g., due to a decrease in the size of theouter channel 208 as a result of the bending).

As shown in FIG. 5B, as the medical cannula 100 is further pressedagainst the patient's body 224, the inner wall 202 and the outer wall206 increasingly bend. As a result, the inner channel 204 is crimped andbecomes obstructed, thereby impeding the flow of fluid from the vessel226 into the patient. In addition, the fluid pressure within the outerchannel 208 is further increased (e.g., due to further decrease in thesize of the outer channel 208 as a result of the bending). If the fluidpressure becomes sufficiently high, the frangible membrane 214 ruptures,releasing the indicator substance 210 into the interface material 502.

As shown in FIG. 5C, after the indicator substance 210 is released intothe interface material 502, the indicator substance 210 diffuses throughthe interface material 502 and mixes with the chemically reactivesubstance 302. This results in a chemical reaction with the chemicallyreactive substance 302 (depicted by the change of shading of the upperportion of the indicator channel 212). The chemical reaction between theindicator substance 210 and the chemically reactive substance 302 can bevisually observed by a user. For example, the chemical reaction canresult in a change of color (e.g., from a clear color to a red color), achange in clarity (e.g., through the creation of a precipitate), achange in photoluminescence, or a change in any other visuallydiscernable property of the combined substances.

Further, in a similar manner as shown in FIG. 4C, the indicator portion120 can include one or more transparent or translucent surfaces 228 thatenable the user to view the interior of the indicator channel 212. Uponthe rupture of the frangible membrane 214, the user observes thechemical reaction within the indicator channel 212 (due to thecombination of the indicator substance 210 and the chemically reactionsubstance 302). Based on this observation, the user ascertains that thebody portion 110 has been bent or kinked, and that the medical cannula100 is damaged. Accordingly, the user can replace the damaged medicalcannula 100 (e.g., by removing the medical cannula 100 and reinserting anew or repaired medical cannula 100).

As described herein, a medical cannula can provide a visual indicationwhen it is damaged. However, a medical cannula can also provide otherindications when it is damaged, such as tactile feedback. This can beuseful, for example, as it enables patients having impaired vision toascertain when the medical cannula has been damaged.

To illustrate, FIG. 6A shows the medical cannula 600 inserted into apatient's body 222. The medical cannula 600 includes a body portion 610,an upper portion 620, and an adapter portion 630. The body portion 610and the adapter portion 630 are generally similar the body portion 110and the adapter portion 130 described with respect to FIGS. 1 and 2A.

For example, the body portion 610 is generally tubular in shape. Thebody portion 610 includes a tubular inner wall 632 that defines an innerchannel 634. The body portion also includes a tubular outer wall 636that encircles the inner wall 632, such that an annular outer channel638 is defined between the inner wall 632 and the outer wall 636. Theinner channel 634 and the outer channel 638 are in fluid isolation withrespect to one another, such that the contents of the inner channel 634and the outer channel 638 do not mix.

Similarly, the adapter portion 630 protrudes from the body portion 610,and defines an adapter channel 640 that is in fluid communication withthe inner channel 634. Fluids introduced into a receiving end 642 of theadapter portion 630 are guided to the exit end 644 of the body portion610.

In this example, however, the outer channel 608 contains an indicatorsubstance 646 that induces a tactile sensation when applied to thepatient's body. As an example, the indicator substance 646 can be a mildirritant (e.g., a mildly acidic solution) that causes a perceptiblesensation (e.g., a tingling or warm sensation) when applied to thepatient's body.

When the medical cannula 600 is undamaged, the indicator substance 646is securely contained within the outer channel 638. Thus, the indicatorsubstance 646 does not induce a tactile sensitive in the body's body.

However, during use, the medical cannula 600 may become damaged. Toillustrate, as shown in FIG. 6A, the inner wall 632 and the outer wall636 have been bent during insertion (e.g., due to the exit end 644 beingdeflected by the patient's skin 224 and/or structures below). Thus, theinner channel 634 is also bent. The bending of the inner wall 632 andthe outer wall 636 increases the fluid pressure within the outer channel638 (e.g., due to a decrease in the size of the outer channel 638 as aresult of the bending).

As shown in FIG. 6B, as the medical cannula 600 is further pressedagainst the patient's body 222, the inner wall 632 and the outer wall636 increasingly bend. As a result, the inner channel 634 is crimped andbecomes obstructed, thereby impeding the flow of fluid from a vessel 648into the patient. In addition, the fluid pressure within the outerchannel 638 is further increased (e.g., due to further decrease in thesize of the outer channel 638 as a result of the bending). If the fluidpressure becomes sufficiently high, the outer wall 636 ruptures,releasing the indicator substance 646 into the patient's body 222. Therelease of the indicator substance 646 induces a tactile sensation(e.g., a mild tingling or warm sensation at or around the site ofinsertion). Based on this sensation, the user ascertains that the bodyportion 610 has been bent or kinked, and that the medical cannula 600 isdamaged. Accordingly, the user can replace the damaged medical cannula600 (e.g., by removing the medical cannula 600 and reinserting a new orrepaired medical cannula 600).

Although FIG. 6B shows the outer wall 636 rupturing when it experiencesa particular degree of bending, this is merely an illustrative example.In practice, the outer wall 636 can be configured such that it ruptureswhen it experiences any specified degree of bending. For example, theouter wall 636 can be designed such that it ruptures it experiences anybending at all. As another example, the outer wall 636 can be designedsuch that it ruptures only if it experiences a degree of bendingsufficient to obstruct the inner channel 634. In some cases, this can beachieved by configuring the outer wall 636 such that it ruptures inresponse to a pre-defined fluid pressure within the outer channel 638.

In some cases, a medical cannula can provide an electronic indicationwhen it is damaged. To illustrate, FIG. 7A shows the medical cannula 700inserted into a patient's body 222. The medical cannula 700 includes abody portion 710, an indicator portion 720, and an adapter portion 730.

The body portion 710 is generally tubular in shape. The body portion 710includes a tubular wall 732 that defines an inner channel 734. The bodyportion also includes an inner layer 736 affixed to the wall 732, and anouter layer 738 affixed to the inner layer 736. The inner layer 736 issubstantially enclosed by the outer layer 738, such that it is notexposed on the exterior of the medical cannula 700. The body portion 710can also include an annular cap 740 that further covers the inner layer736 at the exit end 742 of the body portion 710.

The inner layer 736 generates an electrical response when placed incontact with particular types of fluids. As an example, the inner layer736 can generate an electrical current when placed in contact with theinterstitial fluid of the body. In some cases, the electrical currentcan be induced due to a chemical interaction between the interstitialfluid and material of the inner layer 736.

The outer layer 738 shields the inner layer 736, such that the innerlayer 736 is not exposed to the external environment. As a result, theinner layer 736 does not generate an electrical response (e.g., noelectrical current is induced through the inner layer 736). In somecases, the outer layer 738 can be constructed from a water-resistantmaterial, such that fluids cannot permeate through the outer layer 738and come into contact with the inner layer 736.

The adapter portion 730 protrudes from the body portion 710, and definesan adapter channel 744 that is in fluid communication with the innerchannel 734. Fluids introduced into a receiving end 746 of the adapterportion 730 are guided to the exit end 742 of the body portion 710.

The indicator portion 720 is positioned above the body portion 710 andincludes a control module 748 and an indicator 750. The control module748 is electrically coupled to the inner layer 736, and is configured todetect electrical current flowing through the inner layer 736. Thecontrol module 748 is also electrically coupled to an indicator 750, andis configured to activate the indicator element 750 when an electricalcurrent is detected in the inner layer 736. The indicator can includeone or more components capable of generating visual indications (e.g.,light emitting didoes, liquid crystal displays, or other suchcomponents), one or more components capable of generating tactileindications (e.g., vibration motors), and/or one or more componentscapable of generating auditory indications (e.g., audio speakers). Insome cases, the control module 748 can include an internal power supply(e.g., a battery) for powering the control module 748 and/or theindicator 750. In some cases, the control module 748 can be electricallycoupled to an external power supply (e.g., an external battery, anelectrical grid, or an external electrical device) for powering thecontrol module 748 and/or the indicator 750.

In the example shown in FIG. 7A, the wall 732 has been bent duringinsertion (e.g., due to the exit end 742 being deflected by thepatient's skin 224 and/or structures below), causing a correspondingbend in the inner layer 736 and outer layer 738. The inner channel 734is also bent as a result.

However, in this configuration, the outer layer 738 is still intact, andis shielding the inner layer 736 such that the inner layer 736 is notexposed to the external environment. As a result, the inner layer 736does not generate an electrical response (e.g., no electrical current isinduced through the inner layer 736). Correspondingly, the controlmodule 748 does not detect any electrical current in the inner layer736, and does not activate the indicator element 750.

As shown in FIG. 7B, as the medical cannula 700 is further pressedagainst the patient's body 224, the wall 732, the inner layer 736, andthe outer layer 738 increasingly bend. As a result, the inner channel734 is crimped and becomes obstructed, thereby impeding the flow offluid from a vessel 752 into the patient.

Further, when the outer layer 738 is bent to a sufficient degree, theouter layer 738 ruptures at its bending point and exposes the innerlayer 736 to the external environment. As a result, the inner layer 736comes into contact with the interstitial fluid of the body (representedby arrows 754), and generates an electrical response (e.g., anelectrical current 756 across the inner layer 736). Correspondingly, thecontrol module 748 detects the induced electrical current in the innerlayer 736, and activates the indicator element 750.

The user observes the activated indicator element 750 (e.g., by seeing,hearing, and/or feeling an indication generated by the indicator element750). Based on this observation, the user ascertains that the bodyportion 710 has been bent or kinked, and that the medical cannula 700 isdamaged. Accordingly, the user can replace the damaged medical cannula700 (e.g., by removing the medical cannula 700 and reinserting a new orrepaired medical cannula 700).

In some cases, upon detecting a current in the inner layer 736, thecontrol module 748 can transmit an electronic message to a computingdevice. For example, the control module 748 can include a wirelesstransceiver, and the wireless transceiver can transmit an electronicmessage across a communications network (e.g., a Wi-Fi network, aBluetooth network, a cellular data network, or any other network) to acomputing device (e.g., a server computer, a desktop computer, anotebook computer, a smartphone, a tablet computer, a pager, a wearablecomputer, an electronic monitoring device, or any other device capableof receiving data from a communications network). In response, thecomputing device generates a notification message to a user (e.g., avisual, auditory, and/or tactile notification) to inform the user thatthe medical cannula 700 has been damaged. In some cases, the controlmodule 748 can transmit the electronic message either instead of or inaddition to activating the indicator element 750.

As described herein, the body portion of a medical cannula can begenerally tubular in shape. As an example, FIG. 8A shows a cross-sectionof the body portion 110 (e.g., viewed from a plane orthogonal of theaxis of extension 140). The inner channel 204 has an approximatelycircular cross-section, and an outer channel 208 has an approximatelyannular cross-section.

However, in practice, the channels can have any shape and arrangementrespect to one another. For example, FIG. 8B shows a cross-section ofanother body portion 800. The body portion 800 includes a first channel802 having a crescent-shaped cross-section, and a second channel 804having a generally circular cross-section (with the crescent-shapedremoved). The first channel 802 can contain an indicator solution (e.g.,in a similar manner as the outer channels described herein), and thesecond channel 804 can be used to guide the flow of fluid from a vesselinto a patient's body (e.g., in a similar manner as the inner channelsdescribed herein). Thus, some implementations of the medical cannulaneed not have “inner” and “outer” channels, and instead can have otherarrangements of channels to provide the described features. Other shapesand arrangements of channels are also possible, depending on theimplementation. Further, a medical cannula can include any number ofchannels (e.g., one or more channels containing an indicator solution,and one or more channels for guiding fluid into a patient), depending onthe implementation.

In the examples shown in FIGS. 1-8, a medical cannula is attached to anexternal vessel, and the contents of the vessel are delivered from thevessel to the patient's body. This vessel can be, for example, acontainer (e.g., a bottle, a vial, a capsule, a pouch, or some othercontainer for holding fluid) or a connector to a container (e.g., atube, IV line, a pipe, or any other connector for transporting fluid).The container can be filled with a therapeutic substance (e.g., aninsulin solution, a saline solution, or any other therapeuticsubstance).

However, in some cases, a vessel can be provided as a part of themedical cannula itself. For example, as shown in FIG. 9, a medicalcannula 900 can include a body portion 910 and an indicator portion 920.The body portion 910 and the indicator portion 920 can be generallysimilar the other body portions and the indicator portions describedherein (e.g., the body portion 110 and the indicator portion 120 shownin FIGS. 1-3). However, in this example, the medical cannula includes areservoir 930 in fluid communication with the inner channel 932 of themedical cannula 900. Thus, when the medical 900 is inserted into thepatient's body, the contents of the reservoir 930 are guided by theinner channel 932 into the patient. The reservoir 930 is implemented asa part of the medical cannula 900 itself, such that the user does notneed to attach a separate vessel prior to use.

In a similar manner as described with respect to FIGS. 1-3, theindicator portion 920 allows a user to visually discern whether themedical cannula 900 has been damaged (e.g., through transparent ortranslucent surfaces 934 enabling a user to view the release of anindicator substance into the indicator portion 920).

A medical cannula having an integrated reservoir can be implemented incombination with any of the indication mechanisms described herein. Forexample, a medical cannula having an integrated reservoir can includemechanisms that indicate damage through a chemical reaction (e.g., asshown in FIGS. 4A-4C and 5A-5C), mechanisms that indicate damage throughtactile feedback (e.g., as shown in FIGS. 6A and 6B), and/or mechanismsthat indicate damage electronically (e.g., as shown in FIGS. 7A and 7B).

Although example components and devices are shown in the accompanyingdrawings, it is understood that the components and devices have not beendrawn to scale. For example, certain features may be enlarged relativeto other features to better illustrate particular structures orfunctions. Further, certain features may be larger or smaller relativeto other features than shown in the drawings, depending on the intendedapplication. Thus, in practice, implementations of the components anddevices described herein may have dimensions and proportions differentthan those shown in the drawings.

As an example, a medical cannula can include an inner channel having adiameter of approximately 1.0 mm (e.g., between 0.5 mm to 1.5 mm). Asanother example, a medical cannula can include an outer channel having adiameter of approximately 1.5 mm (e.g., between 1.0 mm and 2.0 mm). Asanother example, a medical cannula can include an indicator portionhaving a diameter of approximately 8.0 mm (e.g., between 7.0 mm and 9.0mm). As another example, a medical cannula can include a body portionhaving a length of approximately 1.0 cm (e.g., between 0.5 cm and 1.5cm) along its axis of extension. Other dimension are also possible,depending on the implementation.

As described herein, implementations of a medical cannula enable a userto visually ascertain whether a cannula has been bent or kinked duringinsertion or use. Although various examples of bending and kinking aredepicted and described herein, these are merely illustrative examples.In some cases, a medical cannula can be considered bent or kinked when adegree of deflection of the medical cannula impacts, may impact, or islikely to impact the flow of therapeutic substance through the medicalcannula to the patient. In practice, this degree of deflection can varybased on many factors, including the properties of the therapeuticsubstance, the dimensions of the medical cannula and its subcomponents(e.g., the body portion), the materials used to construct the medicalcannula, among others. As examples, in some cases, this degree ofdeflection can be approximately 15°, 30°, 45°, 60°, 75°, 90°, 105°,120°, 135°, 150°, 165°, 180°, or any other angle.

Some implementations of subject matter and operations described in thisspecification can be implemented in digital electronic circuitry, or incomputer software, firmware, or hardware, including the structuresdisclosed in this specification and their structural equivalents, or incombinations of one or more of them. For example, in someimplementations, the control module 748 and/or the computing devices incommunication with the control module 748 can be implemented usingdigital electronic circuitry, or in computer software, firmware, orhardware, or in combinations of one or more of them.

Some aspects of implementations described in this specification can beimplemented as one or more groups or modules of digital electroniccircuitry, computer software, firmware, or hardware, or in combinationsof one or more of them. Although different modules can be used, eachmodule need not be distinct, and multiple modules can be implemented onthe same digital electronic circuitry, computer software, firmware, orhardware, or combination thereof.

Some aspects of implementations described in this specification can beimplemented as one or more computer programs, i.e., one or more modulesof computer program instructions, encoded on computer storage medium forexecution by, or to control the operation of, data processing apparatus.A computer storage medium can be, or can be included in, acomputer-readable storage device, a computer-readable storage substrate,a random or serial access memory array or device, or a combination ofone or more of them. Moreover, while a computer storage medium is not apropagated signal, a computer storage medium can be a source ordestination of computer program instructions encoded in an artificiallygenerated propagated signal. The computer storage medium can also be, orbe included in, one or more separate physical components or media (e.g.,multiple CDs, disks, or other storage devices).

The term “data processing apparatus” encompasses all kinds of apparatus,devices, and machines for processing data, including by way of example aprogrammable processor, a computer, a system on a chip, or multipleones, or combinations, of the foregoing. The apparatus can includespecial purpose logic circuitry, e.g., an FPGA (field programmable gatearray) or an ASIC (application specific integrated circuit). Theapparatus can also include, in addition to hardware, code that createsan execution environment for the computer program in question, e.g.,code that constitutes processor firmware, a protocol stack, a databasemanagement system, an operating system, a cross-platform runtimeenvironment, a virtual machine, or a combination of one or more of them.The apparatus and execution environment can realize various differentcomputing model infrastructures, such as web services, distributedcomputing and grid computing infrastructures.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, declarative orprocedural languages. A computer program may, but need not, correspondto a file in a file system. A program can be stored in a portion of afile that holds other programs or data (e.g., one or more scripts storedin a markup language document), in a single file dedicated to theprogram in question, or in multiple coordinated files (e.g., files thatstore one or more modules, sub programs, or portions of code). Acomputer program can be deployed to be executed on one computer or onmultiple computers that are located at one site or distributed acrossmultiple sites and interconnected by a communication network.

Some of the processes and logic flows described in this specificationcan be performed by one or more programmable processors executing one ormore computer programs to perform actions by operating on input data andgenerating output. The processes and logic flows can also be performedby, and apparatus can also be implemented as, special purpose logiccircuitry, e.g., an FPGA (field programmable gate array) or an ASIC(application specific integrated circuit).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andprocessors of any kind of digital computer. Generally, a processor willreceive instructions and data from a read only memory or a random accessmemory or both. A computer includes a processor for performing actionsin accordance with instructions and one or more memory devices forstoring instructions and data. A computer may also include, or beoperatively coupled to receive data from or transfer data to, or both,one or more mass storage devices for storing data, e.g., magnetic,magneto optical disks, or optical disks. However, a computer need nothave such devices. Devices suitable for storing computer programinstructions and data include all forms of non-volatile memory, mediaand memory devices, including by way of example semiconductor memorydevices (e.g., EPROM, EEPROM, flash memory devices, and others),magnetic disks (e.g., internal hard disks, removable disks, and others),magneto optical disks , and CD ROM and DVD-ROM disks. The processor andthe memory can be supplemented by, or incorporated in, special purposelogic circuitry.

To provide for interaction with a user, operations can be implemented ona computer having a display device (e.g., a monitor, or another type ofdisplay device) for displaying information to the user and a keyboardand a pointing device (e.g., a mouse, a trackball, a tablet, a touchsensitive screen, or another type of pointing device) by which the usercan provide input to the computer. Other kinds of devices can be used toprovide for interaction with a user as well; for example, feedbackprovided to the user can be any form of sensory feedback, e.g., visualfeedback, auditory feedback, or tactile feedback; and input from theuser can be received in any form, including acoustic, speech, or tactileinput. In addition, a computer can interact with a user by sendingdocuments to and receiving documents from a device that is used by theuser; for example, by sending web pages to a web browser on a user'sclient device in response to requests received from the web browser.

A computer system may include a single computing device, or multiplecomputers that operate in proximity or generally remote from each otherand typically interact through a communication network. Examples ofcommunication networks include a local area network (“LAN”) and a widearea network (“WAN”), an inter-network (e.g., the Internet), a networkcomprising a satellite link, and peer-to-peer networks (e.g., ad hocpeer-to-peer networks). A relationship of client and server may arise byvirtue of computer programs running on the respective computers andhaving a client-server relationship to each other.

While this specification contains many details, these should not beconstrued as limitations on the scope of what may be claimed, but ratheras descriptions of features specific to particular examples. Certainfeatures that are described in this specification in the context ofseparate implementations can also be combined. Conversely, variousfeatures that are described in the context of a single implementationcan also be implemented in multiple embodiments separately or in anysuitable sub-combination.

A number of embodiments have been described. Nevertheless, it will beunderstood that various modifications may be made without departing fromthe spirit and scope of the invention. Accordingly, other embodimentsare within the scope of the following claims.

What is claimed is:
 1. A medical device comprising: a body portioncomprising: a tubular inner wall defining an inner channel; and atubular outer wall encircling the inner wall, the outer wall defining anouter channel between the outer wall and the inner wall; an indicatorsubstance disposed within the outer channel; and an indicator portiondefining an indicator channel; wherein the body portion is configured toinsert at least in part into a patient, and the indicator portion isconfigured to remain at least in part along an exterior of the patientwhen the body portion is inserted into the patient, and wherein thedevice is configured to transfer at least a portion of the indicatorsubstance from the outer channel to the indicator channel when the bodyportion is bent.
 2. The medical device of claim 1, wherein the outerchannel and the indicator channel are separated by a frangible membrane,and wherein the frangible membrane is configured to rupture when thebody portion is bent.
 3. The medical device of claim 2, wherein theindicator channel and the outer channel are in fluid communication uponrupture of the frangible membrane.
 4. The medical device of claim 1,wherein the indicator portion comprises a transparent or translucentsurface, and wherein an interior of the indicator channel is visiblethrough the transparent or translucent surface when the body portion isinserted into the patient.
 5. The medical device of claim 1, wherein theindicator substance comprises a colored dye.
 6. The medical device ofclaim 1, wherein the indicator channel contains a reactive substance,and wherein transferring at least the portion of the indicator substancefrom the outer channel to the indicator channel causes a reactionbetween the indicator substance and the reactive substance.
 7. Themedical device of claim 6, wherein the reaction causes the indicatorsubstance to change color.
 8. The device of claim 1, wherein theindicator portion is disposed along a first end of the outer channel. 9.The device of claim 1, wherein the indicator portion is disc shaped. 10.The medical device of claim 1, further comprising an adapter portion,wherein the adapter portion defines an access channel through the innerwall and the outer wall, wherein the access channel is in fluidcommunication with the inner channel.
 11. The medical device of claim10, wherein the adapter portion is configured to physically couple to avessel containing a fluid, and wherein the device is configured todeliver the fluid from the vessel to the patient through the accesschannel and the inner channel.
 12. The medical device of claim 11,wherein the fluid comprises insulin.
 13. The medical device of claim 1,further comprising a reservoir containing a fluid, wherein the reservoiris in fluid communication with the inner channel.
 14. The medical deviceof claim 13, wherein the fluid comprises insulin.
 15. The medical deviceof claim 1, further comprising an interface material positioned withinthe indicator channel.
 16. The medical device of claim 15, wherein theinterface material is a sponge.